Concentration of heparin-locking solution and risk of central venous hemodialysis catheter malfunction.

Heparin is used as an interdialytic locking solution for hemodialysis (HD) central venous catheters (CVCs). The purpose of this study was to compare effectiveness of two heparin concentrations (10,000 and 1,000 U/mL) in preventing catheter malfunction. We compared two time periods: a 6-month period with heparin 10,000 U/mL and a 3-month period with heparin 1,000 U/mL. Adults on HD using a CVC (tunneled or untunneled) in Calgary, Alberta, were included. The primary outcome was catheter malfunction. A total of 139 and 134 patients in the heparin 10,000 and 1,000 U/mL periods, respectively, were included. The crude rate of catheter malfunction, per 1,000 HD sessions, was similar for heparin 10,000 (7.6; 95% CI, 5.3 to 10.8) and 1,000 (6.7; 95% CI, 4.3 to 10.3) U/mL periods, respectively (p = 0.76). After adjusting for CVC characteristics and use of recombinant tissue plasminogen activator (rt-PA), there was no association between heparin concentration and CVC malfunction (hazard ratio, 0.77; 95% CI, 0.37 to 1.61). In conclusion, the use of a lower concentration of heparin was not associated with an increased risk of catheter malfunction but may be associated with greater rt-PA use. The association between heparin concentration and rt-PA use requires further study.